Field of the Invention
Embodiments of the present application relate to the art of a torque vectoring device for controlling a split ratio of a torque generated by a drive motor to right and left drive wheels.
Discussion of the Related Art
PCT international publication WO 2015/008661 describes one example of a torque vectoring device of this kind. The drive gear unit taught by WO 2015/008661 as a torque vectoring device comprises a differential unit for distributing torque delivered from a drive motor to right and left drive wheels, and a differential motor for controlling a torque split ratio to the drive wheels. The differential unit is comprised of a pair of single-pinion planetary gear units. In the differential unit, sun gears are rotated by a torque of the drive motor, ring gears of are connected to each other in such a manner as to rotate in opposite directions, and the carriers are connected to drive wheels through driveshafts.
In a vehicle provided with the torque vectoring device taught by WO 2015/008661, torque split ratio to the right and left drive wheels may be altered by the torque vectoring device. In the vehicle of this kind, braking force applied to each of the drive wheels has to be controlled by conventional brake devices individually arranged to control each of the drive wheels. In order to ensure sufficient braking force, the brake device of this kind is provided with a rotary member such as a disc and a drum, a friction member contacted to the rotary member, and an actuator such as a hydraulic cylinder. However, a weight of the brake device of this kind is rather heavy and hence an unsprung load of the vehicle may be increased. In the vehicle thus using the conventional torque vectoring device, therefore, vibrations may be increased.